Backflow prevention valve

ABSTRACT

The backflow prevention valve comprises various embodiments for installation in a liquid conduit for the prevention of reverse flow therethrough. The valve is particularly well suited for installation in a fire hydrant, where it prevents the illicit backflushing of the water system with contaminants. The valve may be constructed for use with either dry barrel hydrants, i.e., where the water is drained from the hydrant when the water is shut off, or wet barrel hydrants, where water remains in the hydrant body at all times. The valve may be constructed with a cylindrical body or with a thinner ring for the body, depending upon the installation desired. Each embodiment includes a series of generally triangular leaves hinged about the inner circumference of the valve body, which close against the central control rod or against one another at their apices when water is not flowing therethrough.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/590,362, filed Jul. 23, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to fluid control valves, andmore particularly to a valve that is particularly well configured toprevent fluid backflow in systems configured for relatively high flowrates and pressures. The present valve may be readily adapted for use inboth wet and dry barrel fire hydrants to prevent contamination of thewater supply therethrough, or may be adapted to other relatively highpressure and high flow fluid systems requiring one-directional flow andbackflow prevention.

2. Description of the Related Art

Fire hydrant systems are generally connected to a central municipal highpressure water supply source. The hydrants themselves are configured toprovide relatively large fluid flows, as necessary to quench a largefire. Hydrants are nearly universally readily accessible, in order toprovide for rapid connection of hoses and opening of the hydrant valvesince time is critical in fighting fires. Hydrants are generally notequipped with backflow prevention valves for the main water flow, as inthe past there has been no apparent reason that such valves would beneeded in hydrant installations.

The ready accessibility to the water supply by means of fire hydrantshas resulted in various users tapping into the water supply for variousreasons. In many cities, street sweepers and construction water tanktrucks will have their water tanks refilled by means of readilyavailable municipal hydrants. This is generally not of great concern, asit does not affect the water supply to any significant degree.

However, the access to fire hydrant water supplies by non-firefightingpersonnel leaves the door open for potentially tragic misuse of such asystem. It has occurred to the present inventor that one or moreterrorists could easily contaminate a municipal water supply, merely bypumping contaminated water or other liquid back into the water supplythrough an easily accessible hydrant. A terrorist would need nothingmore than a relatively small tanker truck or water tank on a trailer,and a pump providing higher pressure than the municipal water supply inthe hydrant system. Contaminated water or other liquid could be pumpedback into the municipal water supply, thereby contaminating the entiremunicipal water supply, or at least a good portion of it, depending uponthe contaminant and its spread or proliferation in the water supply.

Accordingly, the present inventor has developed a solution to thispotential problem by means of a backflow prevention valve which isreadily adaptable for installation in existing fire hydrants of varioustypes, and which may be adapted to other fluid flow systems as well. Thepresent valve essentially comprises a series of generally triangularvanes which are pivotally attached at their bases to the inside of acylindrical insert which is installed between the base of the hydrantand the underlying standpipe or shoe. Various embodiments of the presentbackflow prevention valve provide for installation within both drybarrel and wet barrel type hydrants, with the cylindrical insert havinga flanged fitting(s) for bolting between the hydrant components, orother conventional attachment as required. The present valve iscompletely automatic in its operation, opening as water flow through thehydrant and out the hydrant outlet(s) pushes it open, and automaticallyclosing when the flow is shut off. Any frangible, breakaway couplings orcomponents used with the original hydrant are retained when the presentbackflow prevention valve is installed. The present valve is notaccessible without removing the hydrant from its base, therebyprecluding tampering by unauthorized persons.

A discussion of the related art of which the present inventor is aware,and its differences and distinctions from the present invention, isprovided below.

U.S. Pat. No. 3,185,171 issued on May 25, 1965 to Frank H. Mueller etal., titled “Valving Structure For Fire Hydrant,” describes a hydrantconfiguration having an easily replaceable seat assembly for the controlvalve in the base thereof. The Mueller et al. U.S. patent also disclosesa frangible, breakaway control valve rod coupling and flanged hydrantattachment to provide for ease of replacement of the hydrant in theevent that it is struck from its base (e.g., automobile collision,etc.). However, no backflow prevention valve, automated or otherwise, isdisclosed by Mueller et al. in their patent.

U.S. Pat. No. 3,506,027 issued on Apr. 14, 1970 to John T. Dunton,titled “Fire Hydrant,” describes a “dry barrel” type hydrant havingrelatively small one way valves installed in the drain ports thereof.Dry barrel hydrants conventionally automatically drain the water fromthe barrel after use, to prevent freezing of any remaining water in thebarrel and resultant damage to the hydrant barrel. The Dunton devicecomprises rubber flapper valves which are pushed closed due to waterpressure in the upper portion of the hydrant, and which open when thewater is shut off to allow water to drain from the upper barrel of thehydrant. No large capacity backflow prevention valve for flow from thehydrant supply and through the barrel is disclosed by Dunton.

U.S. Pat. No. 3,850,190 issued on Nov. 26, 1974 to Donald K. Carlson,titled “Backflow Preventer,” describes a flexible toroidal seal, theinner lip of which seals against a hemispherical shell in the center ofthe assembly. Fluid may flow in one direction through a series ofperipheral ports around the central shell. The device is not adaptablefor use in preventing backflow through the central barrel of a firehydrant, as the flexible seal would not hold against significantbackflow pressure in such a relatively large diameter installation.Moreover, the Carlson valve could not be installed in a fire hydrant toprevent backflow, as the central shell would preclude passage of thecontrol valve stem therethrough in a wet barrel type hydrant. TheCarlson valve also has outlets to release any backflowing fluid to theexterior of the valve, which would be unacceptable where a contaminatedfluid of some sort is being introduced into the system.

U.S. Pat. No. 3,980,096 issued on Sep. 14, 1976 to Daniel A. Ellis etal., titled “Fire Hydrant,” describes a hydrant control valveconfiguration which allows the valve to remain with the hydrant shoewhen the barrel is removed therefrom. No backflow prevention valve ofany type is disclosed.

U.S. Pat. No. 3,980,097 issued on Sep. 14, 1976 to Daniel A. Ellis,titled “Fire Hydrant With Drain Valve And Backflow Preventer Mechanism,”describes the installation of small backflow prevention valves in thedrain ports of a dry barrel type hydrant. These valves are much toosmall to serve as a backflow prevention valve for the main flow throughthe hydrant barrel, as provided by the present invention. In any event,the Ellis valves have no central clearance for a valve control shaft ina dry barrel type hydrant, as provided by at least one embodiment of thepresent invention.

U.S. Pat. No. 4,073,307 issued on Feb. 14, 1978 to John H. Royce, titled“Valve For Fire Hydrants,” describes a generally conventional controlvalve in which the resilient valve facing material includes acircumferential lip extension. Royce states that this provides a betterseal when the valve is closed. However, no form of backflow preventionvalve is disclosed by Royce.

U.S. Pat. No. 4,117,856 issued on Oct. 3, 1978 to Donald E. Carlson,titled “Frostproof Backflow Preventer,” describes a one way valveclosely resembling the valve of the '190 U.S. patent to the sameinventor, discussed further above. The same differences noted betweenthat device and the present invention are seen to apply here as well.

U.S. Pat. No. 4,139,931 issued on Feb. 20, 1979 to John H. Royce, titled“Assembly Method For Fire Hydrants,” is a division of the parentapplication upon which the issued '307 U.S. patent (discussed furtherabove) is based. The same differences noted above between the device ofthe '307 U.S. patent and the present invention are seen to apply here aswell.

U.S. Pat. No. 4,483,361 issued on Nov. 20, 1984 to Edward J. Jungbert,Sr., titled “Anti-Syphon Frost-Proof Hydrant,” describes a combinationdrain and anti-siphon valve located at the base of the assembly andextending from one side thereof, allowing water to flow from the barrelafter the lower valve has been closed. However, the valve closes whenpressure on the outlet side of the valve is higher than the pressurewithin the empty barrel. Due to the valve stems at each end of thedevice, it cannot be installed in a dry barrel type fire hydrant with acentral control valve rod or stem. Moreover, the Jungbert, Sr. valve isnot configured for use in relatively high pressure applications, whereasthe present valve is constructed to handle relatively high pressuredifferentials and large flow volumes.

U.S. Pat. No. 4,763,686 issued on Aug. 16, 1988; U.S. Pat. No. 4,770,203issued on Sep. 13, 1988; U.S. Pat. No. 4,790,341 issued on Dec. 13,1988; and U.S. Pat. No. 4,791,952 issued on Dec. 20, 1988, all to DavidF. Laurel and titled “Hydrant And Components Thereof,” are a series ofclosely related patents describing numerous detail improvements in firehydrants. None of the Laurel U.S. patents disclose any form of backflowprevention valve therein.

U.S. Pat. No. 5,129,416 issued on Jul. 14, 1992 to Rand H. Ackroyd,titled “Anti-Siphon Frost-Proof Water Hydrant,” describes a relativelycomplex water tap for outdoor installation, incorporating two backflowprevention valves and an air inlet. The two valves extend completelyacross the entire internal cross sectional area of the outlet, with noprovision for any form of central control valve rod as is required in adry barrel hydrant.

U.S. Pat. No. 5,228,470 issued on Jul. 20, 1993 to John E. Lair et al.,titled “Self Draining Hose Connection Dual Check Valve Back FlowPreventer,” describes a very complex hose coupling multiple check valvestherein. One of the valves has a flexible diaphragm with an openingaround the stem of another valve. The two central valves are situatedupon central stems, which preclude the use of this type of valve in adry barrel type fire hydrant with its concentric valve control rod.

U.S. Pat. Nos. 5,590,679 and 5,632,303 issued respectively on Jan. 7 andMay 27, 1997 to Lawrence Almasy et al., both titled “Wall Water HydrantHaving Backflow And Back Siphonage Preventor,” are continuations of thesame abandoned parent patent application. Both describe a toroidallyshaped, flexible elastic valve surrounding a central shaft. Water flowin the desired direction forces the outer edges of the valve to flexinwardly, toward the stem, with water flowing around the outside of thevalve, rather than flowing through the center of the outwardly sealedvalve as in the present invention. The Almasy et al. valve assembliesappear to be more closely related to the valve assembly of the '470 Lairet al. U.S. patent, than to the present invention.

U.S. Pat. No. 5,971,022 issued on Oct. 26, 1999 to Bunya Hayashi et al.,titled “Selector Valve With Counterflow Prevention Means,” describes apneumatic or hydraulic multiple port valve with a plurality ofconcentric, one way seals. The seals open along their outercircumferences to allow flow, and flex outwardly to seal about theirouter circumferences to block flow in the opposite direction. Thisconfiguration appears to be more closely related to the valves of the'679 and '303 U.S. patents to Almasy et al., described further above,than to the present invention.

U.S. Patent Publication No. 2002/144,731 published on Oct. 10, 2002,titled “Hydrant With Improved Drain Mechanism,” describes theinstallation of a diffuser(s) to the outlet(s) of the drain passage(s)in a dry barrel type fire hydrant. There is no backflow prevention valveprovided with the diffuser, nor is any disclosed for the main waterpassageway of the hydrant.

U.S. Pat. No. 6,561,214 issued on May 13, 2003 to Howard Heil, titled“Hydrant With Improved Drain Mechanism,” is the issued patent based uponthe '731 U.S. patent application Publication to the same inventor,discussed immediately above. The same points noted in that discussionare seen to apply here as well.

Finally, Japanese Patent Publication No. 2002-21,123 published on Jan.23, 2002, titled “Fire Hydrant,” describes (according to the drawingsand English abstract) a single, side hinged flapper valve which is heldin the closed position by a control rod which bears thereagainst. Whenthe rod is raised, the valve is free to open to allow water to flow. Anyback pressure when the valve is open, will push the valve back to itsclosed position against the seat to prevent backflow. The assemblyserves as both the outlet flow control valve and backflow control valve,and would require replacement of the conventional valve in the base ofthe hydrant assembly for most U.S. hydrants. The outlet directly fromthe valve is also non-concentric, unlike U.S. hydrants, and cannot bereadily adapted for use with U.S. hydrants.

None of the above inventions and patents, taken either singly or incombination, is seen to describe the instant invention as claimed. Thusa backflow prevention valve solving the aforementioned problems isdesired.

SUMMARY OF THE INVENTION

The present backflow prevention valve comprises various embodimentswhich may be installed in either dry barrel or wet barrel type firehydrants to prevent the unauthorized back flushing of the hydrant with acontaminated substance, thereby precluding the entrance of such acontaminated substance into the water supply. The present valveembodiments comprise generally cylindrical assemblies having a series ofgenerally triangular segments or leaves pivotally attached to the innerperipheries thereof.

In an embodiment for dry barrel type hydrants, i.e., where the water isdrained from the upper barrel when the control valve is closed, thebackflow prevention valve segments seal against one another, with theirapices sealing against the central control rod or stem for theunderlying control valve. In an embodiment for a wet barrel typehydrant, i.e., where the water remains in the barrel due to the controlvalve being situated at the top of the barrel, the apices of thesegments meet one another in the center of the barrel when the water isshut off.

The present backflow prevention valve body may include at least oneexternally disposed flange for bolting the device between the barrel andthe underlying standpipe for the hydrant, with taller embodiments havingopposed flanges at each end of the cylinder. A frangible coupling of theappropriate length is also provided for installation along the controlrod in dry barrel hydrants, with the coupling also providing a bearingsurface for the apex seals of the valve segments of the presentinvention.

These and other features of the present invention will become readilyapparent upon consideration of the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an environmental, elevation view of a first embodiment of abackflow prevention valve according to the present invention, installedin an otherwise conventional fire hydrant, riser, and shoe assembly.

FIG. 2 is an elevation view in section of the backflow prevention valveassembly of FIG. 1, showing the internal construction thereof.

FIG. 3 is a detailed broken away elevation view of the hinge detail of asingle leaf or vane of the valve of FIG. 2, showing further detailsthereof.

FIG. 4 is an elevation view in section of a second embodiment of thepresent invention, configured for installation in wet barrel hydrantshaving no central control rod or stem.

FIG. 5 is a detailed perspective view of the attachment ring and leavesor segments of the present valve.

FIG. 6 is an elevation view in section of another embodiment of thepresent invention, in which the body comprises a single relatively thinring.

Similar reference characters denote corresponding features consistentlythroughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention comprises various embodiments of a completelyautomatic backflow prevention valve configured to withstand relativelyhigh liquid backflow pressures, yet to allow relatively free liquid flowin the desired direction. It will be noted that the present valve may beincorporated in any of a number of different liquid conduits servingdifferent purposes. However, a primary use of the present valve isenvisioned with fire hydrants of various types and configurations, asillustrated in the drawing Figs.

FIG. 1 of the drawings illustrates a fire hydrant installationcomprising a barrel B extending concentrically from a standpipe S. Thehydrant assembly is conventional, with the exception of the installationof the present backflow prevention valve 10 sandwiched concentricallybetween the standpipe S and the barrel B. Conventionally, fire hydrantbarrels B are secured to their underlying standpipes S by means of amating circumferential barrel flange BF and standpipe flange SF and aseries of peripheral bolts P passing therethrough. This greatly assistsin protecting the underlying standpipe S from damage in the event thehydrant barrel B is damaged, e.g. struck by an automobile, etc., byallowing the barrel B to break away from the underlying structurewithout damage to that structure.

FIG. 2 illustrates further details of the present backflow preventionvalve 10. The valve 10 comprises a hollow cylindrical housing or body 12having an open central area 14 defined by the inner periphery 16 of thehousing 12. The housing or body 12 has a first edge 18 and oppositesecond edge 20 which define a length or height 22 therebetween, withfirst and second attachment flanges 24 and 26 extending radiallyoutwardly respectively from the first and second edges 18 and 20 of thehousing 12. The two flanges 24 and 26 of the housing or body 12 attachrespectively to the standpipe flange SF and barrel flange BF by means ofthe peripheral bolts P. This places the hollow interior 14 of thehousing or body 12 in a concentric relationship with the hollow barrelinterior BI and standpipe interior SI, to allow liquid to flow freelythrough the assembly when the conventional lower shutoff or controlvalve (not shown) is opened.

The housing or body 12 contains a series of rigid, generally triangularvalve segments therein, e.g. segments 28 a, 28 b, 28 c, etc., with 28 athrough 28 c being shown in FIG. 2. Any practicable number of valveleaves or segments may be provided for the present invention, asdesired. While the perspective view of an exemplary valve embodimenthaving six leaves or segments is illustrated in FIG. 5 and discussed indetail further below, greater or fewer segments may be provided asdesired. Each of the valve segments has a base, e.g. bases 30 a, 30 b,and 30 c shown in FIG. 2, a radially disposed first edge, e.g. firstedges 32 a, 32 b, and 32 c in FIG. 2, a radially disposed second edge,e.g. second edges 34 a, 34 b, and 34 c in FIG. 2, and an apex, withtruncated apices 36 a and 36 c being visible in FIG. 2. The first edges32 a, 32 b, etc. each mate with an adjacent second edge 34 a, 34 b, etc.of an adjacent vane 28, e.g. the first edge 32 a of the first vane 28 amates with the second edge 34 b of the second vane 28 b, the first edge32 b of the second vane 28 b mates with the second edge 34 c of thethird vane 28 c, etc. around the circular configuration of the assembly.Various mating seals may be provided along these radially disposededges, with an exemplary configuration being illustrated in FIG. 5 anddiscussed further below.

FIG. 2 also shows the attachment of the various hinge segments 28 a, 28b, etc. within the housing or body 12, with FIG. 3 providing an explodeddetail elevation view of this attachment. Each of the segments 28 a, 28b, etc. is connected at its base to a flexible hinge 38 which extendsinwardly from the inner periphery 16 of the valve housing or body 12.The hinge 38 may comprise a separate component for each valve segment 28a, 28 b, etc., or may comprise a toroidal configuration, with each ofthe valve segments 28 a, 28 b, etc. being secured to an arcuate portionof the continuously circular flexible hinge 38. The hinge 38 is formedof a resilient material having an outer peripheral valve housingattachment portion 40 and an opposite, inner peripheral valve segmentattachment portion 42. A clamp plate or ring 44 having a toroidalconfiguration seats within a recess 46 formed in the first or lower edge18 of the housing or body 12, and sandwiches the outer peripheralportion 40 of the flexible, resilient hinge 38 therebetween to securethe hinge 38 in place.

The hydrant configuration illustrated in FIGS. 2 and 3 is that of a “drybarrel” hydrant, i.e. a hydrant having its shutoff or control valvedisposed below the hydrant barrel B. When the control valve is opened,water flows upwardly through the valve and into the barrel, thenceoutwardly through the conventional hose fittings at the top of thebarrel. When the control valve is closed, water drains from the barrel Bby means of a few relatively small drain passages at the lower end ofthe barrel B. This prevents water from freezing within the barrel B anddamaging the barrel B in below freezing temperatures. Accordingly, thehousing or body 12 preferably includes a few such drain passages 48disposed immediately above the valve assembly 28, one of which isillustrated in FIG. 3, in order to allow water to drain from the barrelB.

As the conventional water shutoff or control valve employed with suchdry barrel hydrants is located below the base of the barrel, a controlvalve rod or stem extends from the operating nut or fixture at the topof the hydrant, down through the interior of the hydrant to the shutoffvalve. Such a configuration is shown in FIG. 2 of the drawings. Thecontrol valve stem is conventionally formed in two lengths or segmentsjoined by a frangible coupling, in order to preclude damage to theshutoff valve in the event the hydrant barrel B is knocked from itsunderlying standpipe S. Accordingly, the first and second control valvestem segments S1 and S2 pass concentrically through the standpipe S andbarrel B, and are connected in the housing or body 12 by an elongatedfrangible coupling 50. The coupling 50 is pinned at each end 52 and 54,and includes a weakened, necked down portion 56 to allow breakage atthat point 56 in the event the hydrant barrel B is dislodged from itsstandpipe S. The coupling 50 is of sufficient length to join the twovalve stem segments S1 and S2 to compensate for the length or height 22of the housing 12, with the lengths of the housing 12 and coupling 50being adjusted to correspond with one another as required.

In the above described dry barrel hydrant configuration, the apices 36a, 36 c, etc. bear against the outer circumference of the valve stemcoupling 50, rather than forming a sharp apex to seal against oneanother. Accordingly, the apices of the various valve segments 28 a,etc. are truncated for installation in such dry barrel type hydrants,with the truncated apices configured to fit closely against the side ofthe coupling 50 (or perhaps against the valve stem itself, dependingupon the configuration of the assembly). FIG. 3 of the drawings clearlyshows such a truncated valve segment tip 36 a for the valve segment 28a, with the truncated tip 36 a configured to fit closely against thecircular shape of the coupling 50 of FIG. 2. It will be seen that someform of resilient seal may be provided to extend from the tip 36 a, asrequired. Such a resilient tip seal is shown in FIG. 5 of the drawings,and discussed further below.

While dry barrel type hydrants are the most prevalent type in use, wetbarrel hydrants, i.e. hydrants in which water remains in the upperbarrel at all times, may also be found in certain locations. Thesehydrants have their water control valves situated at the top of thehydrant with water constantly filling the barrel of the hydrant, thuseliminating the need for a long control valve stem assembly.Accordingly, the truncated or relieved valve segment tip shown in FIGS.2 and 3, is not required for such wet barrel type hydrants. FIG. 4illustrates a wet barrel hydrant embodiment of the present backflowprevention valve, designated as valve assembly 110. The backflowprevention valve assembly 110 includes a housing or body 112 similar tothe housing or body 10 of the dry barrel embodiment of FIGS. 2 and 3,but lacking the drain port(s) 48 of the dry barrel housing 12 shown inFIG. 3. The housing 112 includes an open central area 114 defined by aninner periphery 116, and has opposed first and second edges or ends 118and 120 defining a length or height 122. First and second attachmentflanges, respectively 124 and 126, extend outwardly from the first andsecond ends 118 and 120.

The valve body or housing 112 contains a series of generally triangularvalve leaves or segments, respectively 128 a, 128 b, 128 c, etc.,depending upon the number of segments of the valve assembly. Eachsegment is configured similarly to the valve segments 28 a, 28 b, etc.of the assembly of FIG. 2, having a base edge 130 a, 130 b, etc.pivotally extending from the inner periphery 116 of the valve body orhousing 112, and first and second radial edges, respectively 132 a, 132b, etc. and 134 a, 134 b, etc. However, the extended point apices 136 a,136 b, etc. of the valve segments of the assembly of FIG. 4 differ fromthe truncated apices 36 a, 36 b, etc. of the assembly of FIGS. 2 and 3,as there is no central structure running concentrically through thehydrant and housing in a wet barrel type hydrant. Thus, the apices 136am 136 b, etc. come to a relatively sharp point in such a wet barrelhydrant installation and bear against one another when the valveassembly is closed, rather than against a central shaft or coupling. Thehinge 138 of the assembly 110 of FIG. 4 may have the same configurationas that of the hinge 38 of the assembly 10 of FIGS. 2 and 3, i.e. aflexible, resilient toroidal having its outer edge secured between thefirst or lower edge of the housing or body 112 and a toroidal clampingplate or ring 144. The valve leaves or segments 128 a, 128 b, etc. arepivotally attached to the inboard portion of the hinge 138, and flexupwardly and outwardly toward the inner wall or periphery 116 of thehousing 112 when a liquid passes through the assembly from the standpipeS2 to the hydrant barrel B2, just as in the case of the assembly ofFIGS. 2 and 3.

FIG. 5 provides a perspective view of an exemplary valve segmentassembly 210 for a dry barrel type hydrant, showing the sealing meansused along the edges of the valve segments. It will be noted that ratherthan having a generally cylindrical housing, as in the embodiments ofFIGS. 1 through 4, a relatively thin, toroidal ring 212 is provided fromwhich the valve segments extend inwardly. The ring 212 includes anoutwardly extending circumferential flange 224 to provide for attachmentbetween the flanges of the standpipe and hydrant barrel, and an innerperiphery 216. A series of six generally triangular vanes 228 a through228 f are pivotally secured by their bases 230 a through 230 f along theinner periphery 216 of the ring 212. A flexible, resilient hinge member238 with a toroidal configuration surrounds the segment bases 230 athrough 230 f, with the outer periphery 240 of the circumferential hinge238 being secured to the flange 224 adjacent the inner periphery 216 ofthe ring 212, and the inner periphery 242 folding upwardly and securingto the bases 230 a through 230 f of the valve segments or leaves 228 athrough 228 f.

Each of the valve segments 228 a through 228 f includes a first edge,respectively 232 a through 232 f, an opposite second edge, respectively234 a through 234 f, and an apex, respectively 236 a through 236 f. Eachof the mating edges 232 a through 232 f and 234 a through 234 f includesmeans for sealing when the leaves or segments 228 a through 228 f areclosed or folded together, generally as shown in FIGS. 2, 4, and 6. Eachof the first edges 232 a through 232 f includes parallel first andsecond lips, respectively 58 and 60, which define a groove or channel 62therebetween. The adjacent mating second edges 234 a through 234 f eachhave a convex ridge 64 extending therealong. When the valve leaves orsegments 228 a through 228 f fold together when there is no flow throughthe hydrant, the ridges 64 of each of the segment first edges 232 athrough 232 f nest within the corresponding groove or channel 62 betweenthe lips 58 and 60 of the adjacent segment second edges 234 a through234 f, thereby providing a close seal between mating valve leaves orsegments to preclude backflow of liquid therethrough.

The backflow prevention valve 210 of FIG. 5 is configured for use in adry barrel type hydrant, due to the truncated apices 236 a through 236 fof each of the valve segments 228 a through 228 f. Additional apex seals66 extend from each of the truncated apices, and bear against thecentral coupling 50 (shown in FIG. 2) when the valve segments 228 athrough 228 f are closed. These apex seals 66, along with the edgesealing lips, grooves, and ridges 58 through 64, provide a reasonablysecure seal against backflow through the valve mechanism while stillallowing the segments to hinge outwardly against the inner periphery ofthe backflow prevention valve housing or hydrant barrel, depending uponthe valve embodiment employed.

FIG. 6 provides an elevation view in section of another backflowprevention valve assembly 310, installed between a standpipe S and ahydrant barrel B, with the standpipe S and barrel B being essentiallyidentical to the standpipe S and barrel B shown in FIGS. 1 and 2. Thebackflow prevention valve assembly 310 of FIG. 6 is quite similar to thevalve assembly 210 of FIG. 5, comprising a toroidal ring 312 with acircumferentially extending flange 324 which bolts between the flanges Fof the standpipe S and hydrant barrel B and is secured in place byperipheral bolts P.

A series of valve segments or leaves extend from the inner periphery 316of the ring 312, with three of the segments 328 a through 328 c beingshown in the cross sectional view of FIG. 6. The edge and apex seals maybe essentially identical to those illustrated in FIG. 5 of the drawings,and discussed further above. However, the flexible hinge 338 isconfigured differently, with its outer peripheral housing or ringattachment edge 340 extending downwardly along the inner peripheryrather than being sandwiched between the circumference of the ring 312and a circumferential retaining ring, as shown in FIGS. 2 through 5 ofthe drawings. The inner circumferential portion or edge 342 of the hinge338 secures to the bases 330 a through 330 c of the valve segments 328 athrough 328 e, as in the embodiments of FIGS. 2 through 5.

The above described arrangement may be used in either dry barrel or wetbarrel type hydrants, with the primary difference being in theconfiguration of the apices of the valve segments. In FIG. 6, thetruncated apices 336 a and 336 c are shown in solid lines, abutting thecentral coupling 350. (The coupling need not be so long as shown in FIG.6 when a relatively thin ring valve configuration is used, but thelonger length provides a smooth surface against which the apices of thevalve segments may seal.) Where the valve assembly 310 is used in a wetbarrel type hydrant without the central control valve stem components S1and S2, the apices are extended to form mating points, as shown by theapex portions 336 a and 336 c shown in broken lines in FIG. 6. Thesealing means illustrated in FIG. 5 and discussed further above may beincorporated along the edges of the valve segments of the embodiment 310of FIG. 6, and other embodiments as well.

In conclusion, the present backflow prevention valve in its variousembodiments provides a positive, fully automatic means of preventingliquid flow through a conduit in an undesired direction. The presentvalve may be used in sewage conduits to prevent backups, and/or variousother fluid conduit systems as applicable. However, it may find itsgreatest value in fire hydrant installations, where it will prevent theunauthorized backflushing of hydrants with contaminants, as mightotherwise be easily accomplished by terrorists. The present valve iswell suited for installation in both dry and wet barrel hydrants, withthe primary difference in the valve being the configuration of the valvesegment apices to accommodate the central control valve stem in drybarrel hydrants or to mate with one another in wet barrel hydrants.

The present valve is relatively low, and extends the height of a hydrantby only a few inches so as not to exceed any maximum height standards.Where height is even more critical, the ring embodiments of FIGS. 5 and6 may be employed. While flanges have been illustrated with each of thevarious embodiments disclosed herein, it will be understood that otherconventional means may be used for connecting the present backflowprevention valve with other components, e.g. mating threaded attachmentsas in pipe fittings, etc.

Any of a number of suitable materials may be used to construct thevarious components of the present valve embodiments. The outer housingor ring may be cast of iron, similarly to the technique conventionallyused for forming fire hydrant barrels, standpipes, and similarcomponents. The vanes must be a relatively stiff material, in order toresist the pressure developed by a high pressure pump in an attempt toinduce backflow through the system. Various metals may be used, oralternatively relatively stiff plastics may be used, depending upon thediameter of the valve, the anticipated pressure, and perhaps otherfactors. The sealing edges and apices may be coated or fitted withrelatively softer materials, e.g. Neoprene®, rubber, or other suitablematerial, in order to provide a water tight seal. Where dry barrelinstallations are made, the central coupling is preferably formed with arelatively low friction coating to allow the coupling to slidedownwardly and upwardly between the apex seals as the operating valve isopened and closed.

Accordingly, the present backflow prevention valve will greatly reducethe risks of contamination to a water supply through a hydrant system,and will prove to be of great value and to greatly improve peace of mindfor those responsible for municipal water systems.

It is to be understood that the present invention is not limited to theembodiments described above, but encompasses any and all embodimentswithin the scope of the following claims.

1. A backflow prevention valve, comprising: a hollow cylindrical bodyhaving a first edge, a second edge opposite said first edge defining alength therebetween, and an inner periphery; a plurality of rigid,generally triangular valve segments each having a base, a radiallydisposed first and second edge, and an apex, the first edge and thesecond edge of each of said valve segments having a mating,complementary configuration, the first and the second edge of adjacentsaid valve segments sealing with one another when said valve segmentsare closed; and at least one flexible hinge extending inwardly from theinner periphery of said body and securing the base of each of said valvesegments to said body.
 2. The backflow prevention valve according toclaim 1, further including: a first attachment flange extending radiallyoutwardly from said first edge of said body; and a second attachmentflange extending radially outwardly from said second edge of said body.3. The backflow prevention valve according to claim 1, furtherincluding: a first and a second control valve stem segment passingconcentrically through said body; a frangible coupling connecting saidfirst and said second control valve stem segment; said apex of each ofsaid valve segments having a truncated tip; and a seal extending fromsaid truncated tip of each of said valve segments and sealing againstsaid coupling when said valve segments are closed.
 4. The backflowprevention valve according to claim 1, wherein: said at least oneflexible hinge comprises a resilient material having a toroidalconfiguration with an outer peripheral body attachment portion and aninner peripheral valve segment attachment portion; and a clamp platehaving a toroidal configuration is secured to said first edge of saidbody, sandwiching said outer peripheral body attachment portion of saidat least one flexible hinge between said first edge of said body andsaid clamp plate.
 5. The backflow prevention valve according to claim 1,wherein said apex of each of said valve segments has a pointed tip,bearing against one another when said valve segments are closed.
 6. Thebackflow prevention valve according to claim 1, further including: afirst lip and a second lip spaced apart therefrom disposed along saidfirst edge of each of said valve segments, and defining a groovetherebetween; and a ridge disposed along said second edge of each ofsaid valve segments, and sealing closely within the mating said grooveof an adjacent one of said valve segments when said valve segments areclosed.
 7. A backflow prevention valve, comprising: a thin ring having atoroidal configuration defining an inner periphery; a plurality ofrigid, generally triangular valve segments each having a base, aradially disposed first and second edge, and an apex, the first edge andthe second edge of each of said valve segments having a mating,complementary configuration, the first and the second edge of adjacentsaid valve segments sealing with one another when said valve segmentsare closed; and at least one flexible hinge extending inwardly from theinner periphery of said ring and securing the base of each of said valvesegments to said ring.
 8. The backflow prevention valve according toclaim 7, further including an attachment flange extending radiallyoutwardly from said ring.
 9. The backflow prevention valve according toclaim 7, further including: a first and a second control valve stemsegment passing concentrically through said ring; a frangible couplingconnecting said first and said second control valve stem segment; saidapex of each of said valve segments having a truncated tip; and a sealextending from said truncated tip of each of said valve segments andsealing against said coupling when said valve segments are closed. 10.The backflow prevention valve according to claim 7, wherein: said atleast one flexible hinge comprises a resilient material having atoroidal configuration with an outer peripheral ring attachment portionand an inner peripheral valve segment attachment portion; and a clampplate having a toroidal configuration is secured to said ring,sandwiching said outer peripheral ring attachment portion of said atleast one flexible hinge between said first edge of said ring and saidclamp plate.
 11. The backflow prevention valve according to claim 7,wherein said apex of each of said valve segments has a pointed tip,bearing against one another when said valve segments are closed.
 12. Thebackflow prevention valve according to claim 7, further including: afirst lip and a second lip spaced apart therefrom disposed along saidfirst edge of each of said valve segments, and defining a groovetherebetween; and a ridge disposed along said second edge of each ofsaid valve segments, and sealing closely within the mating said grooveof an adjacent one of said valve segments when said valve segments areclosed.
 13. A hydrant having a backflow prevention valve installedtherein, comprising in combination: a hydrant barrel having a hollowinterior and a base; a hydrant standpipe disposed concentrically belowsaid barrel; a hydrant backflow prevention valve installedconcentrically between said hydrant barrel and said hydrant standpipe,the valve having: a valve housing having an open center concentric withsaid hydrant barrel and said hydrant standpipe, and having an innerperiphery; a plurality of rigid, generally triangular valve segmentseach having a base, a radially disposed first and second edge, and anapex, the first edge and the second edge of each of said valve segmentshaving a mating, complementary configuration, the first and the secondedge of adjacent said valve segments sealing with one another when saidvalve segments are closed; and at least one flexible hinge extendinginwardly from the inner periphery of said valve housing and securing thebase of each of said valve segments to said valve housing.
 14. Thehydrant and backflow prevention valve combination according to claim 13,wherein said valve housing comprises: a hollow cylindrical body having afirst edge, a second edge opposite said first edge defining a lengththerebetween, and an inner periphery; a first attachment flangeextending radially outwardly from said first edge of said body; and asecond attachment flange extending radially outwardly from said secondedge of said body.
 15. The hydrant and backflow prevention valvecombination according to claim 13, wherein said valve housing comprisesa thin ring having a toroidal configuration with an inner periphery. 16.The hydrant and backflow prevention valve combination according to claim13, further including: a first and a second control valve stem segmentpassing concentrically through said hydrant barrel, said hydrantstandpipe, and said valve housing; a frangible coupling connecting saidfirst and said second control valve stem segment; said apex of each ofsaid valve segments having a truncated tip; and a seal extending fromsaid truncated tip of each of said valve segments and sealing againstsaid coupling when said valve segments are closed.
 17. The hydrant andbackflow prevention valve combination according to claim 13, wherein:said at least one flexible hinge comprises a resilient material having atoroidal configuration with an outer peripheral valve housing attachmentportion and an inner peripheral valve segment attachment portion; and aclamp plate having a toroidal configuration is secured to said valvehousing, sandwiching said outer peripheral valve housing attachmentportion of said at least one flexible hinge between said valve housingand said clamp plate.
 18. The hydrant and backflow prevention valvecombination according to claim 13, wherein said apex of each of saidvalve segments has a pointed tip, bearing against one another when saidvalve segments are closed.
 19. The hydrant and backflow prevention valvecombination according to claim 13, further including: a first lip and asecond lip spaced apart therefrom disposed along said first edge of eachof said valve segments, and defining a groove therebetween; and a ridgedisposed along said second edge of each of said valve segments, andsealing closely within the mating said groove of an adjacent one of saidvalve segments when said valve segments are closed.